Internal combustion engines may use an exhaust driven compressor or turbocharger assembly to increase the manifold air pressure (MAP), thereby providing increased engine performance for a given engine displacement. A typical turbocharger assembly includes a turbine assembly in fluid communication with the exhaust gases and a compressor assembly in fluid communication with the intake gases. A portion of the energy contained within the exhaust gases operates to spin or rotate a turbine wheel disposed within the turbine assembly. The turbine wheel is connected to a compressor impeller of the compressor assembly through a common shaft. As such, the turbine wheel and compressor impeller rotate in unison. In operation, as the exhaust gases rotate the turbine wheel, the rotating compressor impeller inducts or draws intake gases into the compressor assembly where the intake gases are pressurized for subsequent introduction to the internal combustion engine.
A conventional turbocharger assembly may also include a bearing assembly to support the load of the shaft interconnecting the turbine wheel and the compressor impeller. In some turbocharger assemblies, a gas or air bearing assembly supports the load of the shaft. Air bearing assemblies employ a thin film of gas (such as air) that acts as the lubricant, separating two surfaces in relative motion. In operation, a gas film flows between the air bearing and the shaft of the turbocharger assembly to protect the shaft and the air bearing assembly itself from wear.